1. Field of the Invention
The present invention relates generally to remote sensors and, more particularly, to an optical sensor system to detect the presence and absence of a towed array cable within a submarine's water-filled cable tube.
2. Description of the Prior Art
The currently available outboard sensor assembly utilized in many submarines to detect a thin-line towed array employs an acoustic sensor to alert the system operator of one of two conditions for the water-filled cable tube, either “tube empty” or “tube full.” The acoustic sensors require open access to the tube's water-filled environment for efficient acoustic coupling into the tube. The open access requires cutting out section of the tube, which is a leak risk factor for submarine safety. Because of the location of the outboard sensor assembly on a submarine, the repair and replacement is problematic. Moreover, acoustic sensors have been found to be unreliable, which has led to the continual refit of submarines coming out of the shipyards.
The following U.S. patents describe various prior art systems that may be related to the above and/or other MFC power conditioners:
U.S. Pat. No. 4,518,862 teaches an apparatus for determining the position of a sheet when the sheet is placed on a support having at least two spaced apart CCD linear image sensors recessed in the sheet support and partially covered by the edge portions of the sheet. The CCDs operate as line cameras, and are scanned to generate signals correlated with the points of intersection of the sheet edges and the axes of the image sensors. Preferably the apparatus has circuitry for storing calibration values of the CCD signals obtained when the image sensors are not covered by the sheet, circuitry for storing corresponding scanning signal values when the image sensors are covered by the sheet, circuitry for comparing corresponding calibration and scanning values for obtaining difference values, and circuitry for detecting maxima in the gradient of the difference values for adjacent image points to find the locations of the points of intersection of the sheet edges and the axes of image sensors. These locations are used by software driving an X-Y plotter head or by a sheet positioning mechanism to correct for variations in sheet position.
U.S. Pat. No. 5,406,092 discloses semiconductor wafer-detecting apparatus provided with a main support body formed of synthetic resin. A pair of substantially-parallel longitudinal channels and a plurality of substantially-parallel transverse channels are formed in the main support body. The longitudinal channels are located away from each other by a predetermined distance, and the transverse channels are arranged at intervals corresponding to the intervals at which wafers are arranged. Between the adjacent transverse channels, a plurality of pairs of holding portions are defined such that each pair is associated with the longitudinal channels. A pair of light-emitting elements and a pair of light-receiving elements are alternately arranged with reference to the holding portions. The light-emitting elements of each pair have their light-emitting faces oriented in opposite directions; likewise, the light-receiving elements of each pair have their light-receiving faces oriented in opposite directions. The light-emitting elements of each pair and associated light-receiving elements jointly constitute respective optical sensors. The presence or absence of a wafer is determined by detecting whether or not light is shielded between the light-emitting and light-receiving elements of each optical sensor.
U.S. Pat. No. 5,440,391 teaches a device for determining a position with respect to a reference plane of at least one lead of an electronic component, wherein the lead is illuminated from a first and respectively second position situated sideways and out of the plane wherein the electronic component is disposed and wherein a first and respectively a second shadow image is formed of at least a part of the lead on an image plane, which second position is different from the first position and wherein the first and respectively the second shadow image is located and a third and respectively a fourth position is determined to this end and the position is determined from the third and fourth position.
U.S. Pat. No. 5,501,633 teaches a coin mechanism having a coin storage tube and an optical sensor for sensing the level of coins in the tube, the sensor comprising a light source arranged to direct a light beam across the tube, a reflector for returning the beam across the tube and a light detector for detecting the returned beam is disclosed. The reflector for returning the beam is a concave mirror having a curvature such as to give the beam an area, where it approaches the detector, substantially greater than the effective area of the detector. This enables, in a compact sensor, the light intensity at the detector to be enhanced and at the same time the sensitivity to misalignment of components to be reduced.
U.S. Pat. No. 5,701,122 teaches an electronic curb feeler system that uses two pairs of optical sensor units to detect an object located near the front end of a vehicle during parking. One pair of optical sensor units detects an object directly in front of a left portion of the front end of the vehicle while another pair of optical sensors detects an object directly in front of a right portion of the front end of the vehicle. By supplying the operator of the vehicle with the location of the object as well as the exact distance the object is from the front end of the vehicle the operator can avoid hitting the object while parking very close to the object.
U.S. Pat. No. 6,806,947 teaches an apparatus and method for determining the presence of a fluid conduit at a predetermined location and at least one characteristic of the fluid in the conduit are disclosed. The apparatus includes a light source for generating radiated light in a direction towards the predetermined location, such that when the fluid conduit is present at the predetermined location the radiated light passes in a direction through the fluid conduit, a first optical sensor for detecting the radiated light through the fluid conduit, and a second optical sensor for detecting the radiated light which is reflected by the fluid conduit.
U.S. Pat. No. 6,979,814 teaches a multi-optical-path photoelectric safety apparatus that has a light emitting unit, a light receiving unit and a control unit for controlling each optical path. A light block substance sensing function for a multi-optical-path light curtain is also provided to sense an object between the light emitting unit and the light receiving unit. A muting area setting unit is also provided that can be taught how to set an area for exerting a muting function. The muting function can be provided only in a partial area of the light curtain by using the muting area setting unit.
U.S. Pat. No. 7,335,116 teaches an object locating system that detects the presence of an object as it passes through two consecutive planar fields of view. Two pairs of optical sensor arrays with multiple, directed, pixel detectors observe the object from two angles as the object passes through each consecutive field of view. The locations of penetrations of the respective fields of view are calculated by triangulation. Using this data, the known location of the take-off point and/or the delay between penetrations, the trajectory of the object in time and space is calculated. Applications include projecting the range of a driven golf ball, measuring the respective arriving and departing velocities of a hit baseball, and determining the trajectory and origin of an arriving projectile, as in the case of the threat to a military vehicle.
U.S. Pat. No. 7,355,727 teaches a system for checking the position of a mechanical part, for example a tool of a lathe, along a checking direction. The system employs an optoelectronic device with a laser beam and a sensor for detecting the interruption of the beam. Mutual displacements between the part to be checked and the optoelectronic device within a checking area are controlled according to a sequence including linear inspection movements along a direction perpendicular to the checking direction and at inspection positions. The inspection positions are spaced apart along the checking direction at progressively decreasing mutual distances, according to a sequence that converges to the searched position.
The above cited prior art does not disclose an outboard optical sensor system operable for determining the absence or presence of a thin-line towed array cable within a tube.